1. Technical Field
The present invention relates to a control apparatus for starting an engine mounted on a vehicle, and more particularly to a control apparatus having power-off control function adapted to starters for starting engines.
2. Description of the Related Art
Generally, starters for starting engines are powered off when the starter completes starting of the engine. A control apparatus is used to control powering off of the starter when a predetermined power-off condition is detected. The power-off condition varies depending on types of starter operations. Conventionally, the starter operations include the following three types.
(a) One of three types of starter operations implements a rotary-type switch (ignition key switch) for starting the engine: the driver triggers the starter operation such that the driver turns the ignition key switch from the ON position to the START position whereby the starter is powered to crank the engine, and therefore the engine starts. The driver turns the ignition key from the START position to the ON position to stop the starter operation (powering off the starter) when the driver determines the engine is started.
(b) One of three types of starter operations implements a press-type start switch (ignition switch) for starting the engine: the driver triggers the starter operation such that the driver presses the start switch for powering the starter to start cranking the engine, thereby starting the engine. The starter operation is controlled to be stopped (powering off the starter) when a complete engine-start is detected depending on whether or not the engine rotational rate exceeds a predetermined threshold value.
(c) One of three types of starters implements an idle stop system (automatic engine stop/restart system): The starter is controlled to start the operation when a predetermined automatic start condition is met during an idle stop condition such that the starter is powered and starts cranking the engine thereby starting the engine. The starter operation is controlled to be stopped (powering off the starter) when a complete engine-start is detected depending on whether or not the engine rotational rate exceeds a predetermined threshold value. Specifically, a Japanese Patent No. 4214401 discloses the above-described technique used for an automatic stop/restart control apparatus.
Conventionally, in the above-described starter operations, the starter is supplied with power continuously until completion of the starter operation. Meanwhile, when the engine completely starts, the rotational rate of the engine is higher than the no-load rotational rate (i.e., rotational rate when no-load is applied) of the starter so that the pinion gear of the starter is rotatable by rotational force of the engine after rotational rate of the pinion gear exceeds the no-load rotational rate of the starter. However, the power is continuously supplied to the starter until the engine rotational rate reaches the predetermined threshold value. Therefore, while the starter is continuously powered, the battery power is consumed unnecessarily, which affects the battery to shorten its life-time of operation and also affects durability of the starter.
Specifically, since the idle stop system requires frequent engine restart operations, load on the battery significantly increases and therefore, the durability of the starter decreases. To enhance the durability of the starter, it may cause an increase of manufacturing cost thereof.